This patch adds the OPEN_PLMENU options which behaves similar to OPEN_MENU but
can be used to parse command generated proplists. This can be used e.g. in
conjunction with wmmenugen like:
(
"Generated PL Submenu",
OPEN_PLMENU,
"|| find /usr/share/applications -type f -name '*desktop' | xargs
wmmenugen -parser:xdg"
)